1. Technical Field
The present invention relates to an adhesive material for use in a processing device necessary to form an electrophotographic image, and to a process cartridge and an electrophotographic image forming apparatus, in which the adhesive material is used.
2. Related Art
An image forming apparatus such as a printer utilizing an electrophotographic system has an electrophotographic photoreceptor and processing devices arranged around the photoreceptor such as a charging device, an image exposing device, a developing device, a transfer device, and a cleaning device. An electrophotographic image is formed by the functions, e.g., charging, developing or the like, of the processing devices, such as the charging device and the developing device, on the photoreceptor. Each processing device is composed of a plurality of members or components coupled to each other with a coupling member. As such a coupling member, a mechanical coupling member having projections and depressions at coupling portions, an adhesive material, for example, a double-faced adhesive tape, or the like may be used. The coupling members are often used in combination to assemble a processing device for reasons of cost and convenience. In order to couple mechanically all the members or components of a processing device, each member or component is required to have a structure suitable for mechanical coupling. In reality, however, there are some coupling portions which are not suitable for mechanical coupling or which significantly increase the production costs thereof when mechanically coupled. In such cases, chemical means are generally used for coupling.
In recent years, an adhesive material such as a double-faced adhesive tape has been widely used as the chemical coupling member. However, when a processing device fabricated by utilizing a commercially available adhesive material is incorporated in an electrophotographic image forming apparatus and images are formed, image unevenness often occurs. The present inventors examined the causes of the image unevenness and found that commercially available adhesive materials contain some volatile substance which vaporizes in the image forming apparatus to have an effect on the photoreceptor and to deteriorate the performance thereof.